A high-stable crystal face structure vanadium-based positive electrode material and a preparation method thereof

Abstract

The application discloses a kind of high-stability crystal face structure vanadium series positive electrode materials and preparation method thereof, belong to zinc ion battery technical field, including the following steps: step S1, vanadium pentoxide powder is added to beaker, then deionized water is stirred and mixed, zinc sulfate and sodium anthraquinone-2-sulfonate are added and stirred and mixed, finally hydrogen peroxide is stirred and mixed, and modified solution is obtained;Step S2, the modified solution is added to reaction kettle, then pretreated carbon cloth is immersed in modified solution and hydrothermal reaction is carried out, pressure reduction, cooling to room temperature, multiple water washing, drying, and high-stability crystal face structure vanadium series positive electrode material is obtained;The application improves the ion migration rate of positive electrode material by the pre-intercalation of zinc ion and the synergistic anchoring of sodium anthraquinone-2-sulfonate, and at the same time forms stable crystal space structure, provides wide and stable microchannel in the process of ion intercalation-extraction, enhances the zinc storage rate performance and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of zinc-ion battery technology, specifically relating to a highly stable vanadium-based cathode material with a crystalline structure and its preparation method. Background Technology

[0002] Flexible battery systems focus on flexible lithium-ion batteries, flexible sodium-ion batteries, and flexible zinc-ion batteries. Compared to flexible lithium-ion and sodium-ion batteries, flexible zinc-ion batteries offer advantages such as simple fabrication processes (no vacuum required), non-toxic electrolytes (aqueous electrolytes), long cycle life (up to 10,000 charge-discharge cycles), high capacity (theoretical capacity approximately 820 mAh / g), and high safety (no risk of fire or explosion), making them a promising option for next-generation energy storage. Vanadium-based cathode materials, such as vanadium pentoxide and ammonium vanadate, have attracted widespread attention due to their high discharge specific capacity and long cycle life. Although vanadium-based cathode materials can accommodate large volumes of zinc ions, their structural instability, weak conductivity, and low ion diffusion coefficient cause rapid capacity decay during cycling. Therefore, effectively introducing guest intercalation materials while forming a stable crystal spatial structure to provide wide-area and stable microscopic channels during ion insertion and extraction remains a crucial challenge.

[0003] Currently, an effective strategy for adjusting the structure of layered, confined interlayer regions is the chemical pre-intercalation synthesis method, which opens up a powerful avenue for constructing new phases, hybrid materials, and two-dimensional heterostructures, as well as for controlling electrochemical charge storage properties. In existing technologies, lithium ions have been successfully intercalated into the interlayer of hydrated vanadium pentoxide structures using a hydrothermal method to prepare aqueous ZIBs cathode materials with long cycle life. The combination of lithium ion doping and structural water retention in Li... x V₂O₅·nH₂O further expands the interlayer distance of the cathode material, effectively solving the bottleneck problems of slow ion diffusion and unstable material structure during the charging and discharging process of traditional vanadium pentoxide as a cathode material in aqueous zinc-ion batteries, and improving cycle stability. However, this method can only improve the ion migration rate. The zinc ion insertion-extraction process will cause the lattice "breathing effect", causing the generation of interlayer stress. It cannot effectively introduce guest intercalation materials while forming a stable crystal spatial structure, and it is difficult to provide a wide-range and stable microscopic channel during the ion insertion-extraction process. Chinese invention patent with announcement number CN110364726B discloses a method for preparing and applying a dual-ion doped vanadium pentoxide cathode material. This method uses a hydrothermal method to Na₂O₅. + Zn 2+ Dual ion doping, and through Na + Zn 2+ Controlling Zn by the molar ratio with V2O5 x Na yThe doping amount in V2O5 nanowires can regulate the stability of the internal structure of the material, effectively suppress the dissolution of vanadium compounds in the electrolyte, and effectively improve the capacity of the material. However, even after dual-ion doping, the crystal structure of vanadium-based materials is not modified and anchored, which causes the lattice size of vanadium-based materials to collapse during multiple charge-discharge cycles, resulting in a decrease in cycle stability. Moreover, in the process of ion insertion and extraction, traditional vanadium pentoxide cathode materials inevitably cause structural expansion and recovery. During rapid charge-discharge or multiple charge-discharge cycles, this irreversible structural change will inevitably lead to a decrease in ion migration rate and a decrease in the energy storage performance of the electroactive material. Summary of the Invention

[0004] This invention proposes a method for preparing a vanadium-based cathode material with a highly stable crystal plane structure. A novel strategy of "synergistic intercalation-anchoring" of the cathode material by zinc ions and the organic molecule sodium anthraquinone-2-sulfonate is designed. This strategy can simultaneously achieve the pre-intercalation of intercalated and extracted metal ions and the co-anchoring of the cathode material's crystal structure by organic molecules. This enables the controllable growth of the highly stable vanadium-based cathode material with a crystal plane structure and solves the problems of slow ion diffusion and unstable material structure in traditional vanadium pentoxide materials used as cathodes in aqueous zinc-ion batteries during charge and discharge.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a vanadium-based cathode material with a highly stable crystal plane structure includes the following steps:

[0007] Step S1: Preparation of modified solution

[0008] Add vanadium pentoxide powder to a beaker, then add deionized water and stir for 10-30 minutes to fully dissolve the vanadium pentoxide powder. Then add zinc sulfate and sodium anthraquinone-2-sulfonate and stir for 10-30 minutes. Finally, add hydrogen peroxide and stir to obtain a uniform, transparent red modified solution.

[0009] Step S2: Preparation of cathode material

[0010] The modification solution was added to a polytetrafluoroethylene-lined reactor, and then pretreated carbon cloth was added and immersed in the modification solution for hydrothermal reaction. The pressure was reduced, cooled to room temperature, and the surface was washed repeatedly with water to remove the loosely attached active material. After drying, a vanadium-based cathode material with a highly stable crystal structure was obtained.

[0011] Furthermore, the ratio of the amount of pretreated carbon cloth, vanadium pentoxide powder, deionized water, zinc sulfate, sodium anthraquinone-2-sulfonate and hydrogen peroxide is 10g:4.5-5g:562.5-625mL:0.35-0.5g:0.3-0.5g:4.5-5g.

[0012] Furthermore, the carbon cloth pretreatment is obtained by the following method:

[0013] The carbon cloth was cleaned sequentially with hydrochloric acid, acetone, ethanol and deionized water to remove surface impurities. After cleaning, it was dried to obtain pretreated carbon cloth.

[0014] Furthermore, the purity of the vanadium pentoxide powder is 90-98%.

[0015] Furthermore, the temperature of the hydrothermal reaction is 120-140℃, and the time of the hydrothermal reaction is 6-10h.

[0016] A highly stable vanadium-based cathode material with a crystal plane structure was prepared by the above method.

[0017] Beneficial effects:

[0018] This invention uses carbon fiber cloth as a carrier and selects zinc ions and sodium anthraquinone-2-sulfonate with abundant functional groups as a modification system to expand the interplanar spacing and stabilize the crystal structure of vanadium-based materials. Firstly, zinc ions can be pre-intercalated into the interlayer of vanadium-based materials, expanding the interplanar spacing and accelerating the ion diffusion rate during insertion-extraction, thus increasing the theoretical capacity. Secondly, sodium anthraquinone-2-sulfonate is chemically bonded to the pre-intercalated vanadium-based materials, using chemical bonds to synergistically anchor the crystal structure, stabilizing the crystal structure of both the vanadium-based materials and the inserted zinc ions, preventing crystal structure damage during ion migration, thereby improving crystal stability. Through zinc ion... The synergistic effect of sodium anthraquinone-2-sulfonate on optimizing the crystal structure of vanadium-based materials improves ion migration rate and solves the problem of interlayer stress caused by the "breathing effect" of the lattice during zinc ion insertion and extraction. By introducing guest intercalation materials and forming a stable crystal spatial structure, a wide-range and stable microscopic channel is provided during ion insertion and extraction, enhancing the rate performance and cycle stability of zinc storage. After 1000 cycles of charge and discharge testing, the cathode material still maintains a high degree of consistency in charge transfer resistance, effectively solving the bottleneck problems of slow ion diffusion and unstable material structure of traditional vanadium pentoxide materials as cathodes in aqueous zinc-ion batteries during charge and discharge. Attached Figure Description

[0019] The present invention will now be further described with reference to the accompanying drawings.

[0020] Figure 1 This is a SEM image of the positive electrode material prepared in Example 3 of this invention;

[0021] Figure 2 This is a SEM image of the cathode material prepared in Comparative Example 1 of this invention;

[0022] Figure 3This is a SEM image of the cathode material prepared in Comparative Example 2 of this invention;

[0023] Figure 4 This is a SEM image of the cathode material prepared in Comparative Example 3 of this invention;

[0024] Figure 5 This is a TEM image of the positive electrode material prepared in Example 3 of the present invention;

[0025] Figure 6 These are the XRD spectra of the cathode materials prepared in Example 3 and Comparative Examples 1-3 of this invention;

[0026] Figure 7 These are 0-1000 in-situ EIS images of the cathode materials prepared in Example 3 and Comparative Examples 1-3 of this invention;

[0027] Figure 8 The positive electrode materials prepared in Example 3 and Comparative Examples 1-3 of this invention are constant current charge-discharge (GCD) diagrams under the conditions of 5 cycles at current densities of 0.5 A / g, 1 A / g, 2 A / g, 4 A / g and 5 A / g, respectively.

[0028] Figure 9 The graph shows the performance of the cathode materials prepared in Example 3 and Comparative Examples 1-3 of this invention after 200 long cycles at a current density of 1 A / g.

[0029] Figure 10 This is a graph showing the long-cycle performance of the cathode materials prepared in Example 3 and Comparative Examples 1-3 of the present invention after 2000 cycles at a current density of 5 A / g. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment provides a highly stable vanadium-based cathode material with a crystal plane structure, which is prepared by the following steps:

[0033] Step S1: Clean the carbon cloth sequentially with hydrochloric acid, acetone, ethanol and deionized water. After cleaning, dry it to obtain pretreated carbon cloth. Weigh 10g of the pretreated carbon cloth for later use.

[0034] Step S2: Add 4.5g of vanadium pentoxide powder with a purity of 90% to a beaker, then add 562.5mL of deionized water and stir for 10min. Then add 0.35g of zinc sulfate and 0.3g of sodium anthraquinone-2-sulfonate and stir for 10min. Finally, add 4.5g of hydrogen peroxide and stir to obtain a uniform, transparent red modified solution.

[0035] Step S3: Add all the modification solution to the polytetrafluoroethylene-lined reactor, then add 10g of pretreated carbon cloth and immerse it in the modification solution. Perform a hydrothermal reaction at 120℃ for 6 hours, reduce the pressure, cool to room temperature, wash with water multiple times, and dry to obtain a vanadium-based cathode material with a high-stability crystal structure.

[0036] Example 2

[0037] This embodiment provides a highly stable vanadium-based cathode material with a crystal plane structure, which is prepared by the following steps:

[0038] Step S1: Clean the carbon cloth sequentially with hydrochloric acid, acetone, ethanol and deionized water. After cleaning, dry it to obtain pretreated carbon cloth. Weigh 10g of the pretreated carbon cloth for later use.

[0039] Step S2: Add 4.8g of vanadium pentoxide powder with a purity of 95% to a beaker, then add 600mL of deionized water and stir for 20min. Then add 0.42g of zinc sulfate and 0.4g of sodium anthraquinone-2-sulfonate and stir for 20min. Finally, add 4.8g of hydrogen peroxide and stir to obtain a uniform, transparent red modified solution.

[0040] Step S3: Add all the modification solution to the polytetrafluoroethylene-lined reactor, then add 10g of pretreated carbon cloth and immerse it in the modification solution. Perform a hydrothermal reaction at 130℃ for 8 hours, reduce the pressure, cool to room temperature, wash with water multiple times, and dry to obtain a vanadium-based cathode material with a high-stability crystal structure.

[0041] Example 3

[0042] This embodiment provides a highly stable vanadium-based cathode material with a crystal plane structure, which is prepared by the following steps:

[0043] Step S1: Clean the carbon cloth sequentially with hydrochloric acid, acetone, ethanol and deionized water. After cleaning, dry it to obtain pretreated carbon cloth. Weigh 10g of the pretreated carbon cloth for later use.

[0044] Step S2: Add 5g of vanadium pentoxide powder with a purity of 98% to a beaker, then add 625mL of deionized water and stir for 30min. Then add 0.5g of zinc sulfate and 0.5g of sodium anthraquinone-2-sulfonate and stir for 30min. Finally, add 5g of hydrogen peroxide and stir to obtain a uniform, transparent red modified solution.

[0045] Step S3: Add all the modification solution to a polytetrafluoroethylene-lined reactor, then add 10g of pretreated carbon cloth and immerse it in the modification solution. Perform a hydrothermal reaction at 140℃ for 10 hours. Reduce the pressure, cool to room temperature, wash repeatedly with water, and dry to obtain a highly stable vanadium-based cathode material with a crystal structure, denoted by Zn_AQ_VOH. Its microstructure under SEM is shown below. Figure 1 As shown, the image under TEM is as follows Figure 5 As shown, both zinc sulfate and sodium anthraquinone-2-sulfonate achieved intercalation and recombination of VOH, and the zinc ions and sodium anthraquinone-2-sulfonate were homogeneously distributed in the system.

[0046] Comparative Example 1

[0047] This comparative example differs from Example 3 in that zinc sulfate and sodium anthraquinone-2-sulfonate are not added in step S2; all other materials and steps are the same, resulting in a common vanadium-based cathode material, denoted by VOH. Its microstructure under SEM is shown below. Figure 2 As shown.

[0048] Comparative Example 2

[0049] This comparative example differs from Example 3 in that only zinc sulfate is added in step S2, and sodium anthraquinone-2-sulfonate is not added. All other materials and steps are the same, resulting in a zinc-ion intercalated vanadium-based cathode material, denoted by Zn_VOH. Its microstructure under SEM is shown below. Figure 3 As shown.

[0050] Comparative Example 3

[0051] The difference between this comparative example and Example 3 is that zinc sulfate is not added in step S2; only sodium anthraquinone-2-sulfonate is added. All other materials and steps are the same, resulting in a vanadium-based cathode material modified with sodium anthraquinone-2-sulfonate, denoted by AQ_VOH. Its microstructure under SEM is shown below. Figure 4 As shown.

[0052] XRD tests were performed on the cathode materials prepared in Examples 1-3 and Comparative Examples 1-3, respectively. The XRD spectra are shown in the figure. Figure 6 As shown in Table 1, the interlayer spacing of each group of cathode materials was recorded.

[0053] Table 1

[0054]

[0055] As can be seen from the data in Table 1, the introduction of zinc sulfate reduced the interlayer spacing of VOH from Increase to This indicates that zinc ions successfully inserted into the interlayer space of VOH. However, after sodium anthraquinone-2-sulfonate and zinc sulfate were introduced into the system together, the interlayer spacing of VOH decreased, to a certain value. This indicates that sodium anthraquinone-2-sulfonate plays a role in bonding and anchoring zinc ions after they are inserted into VOH, thus slightly reducing the interlayer spacing.

[0056] The cathode materials prepared in Example 3 and Comparative Examples 1-3 were subjected to 0-1000 cycles of in-situ EIS testing, and the results are as follows: Figure 7 As shown, in Comparative Example 1 (VOH), the charge transfer resistance (Rct, the semicircular arc in the figure) of the electrode changed continuously during 0-1000 charge-discharge cycles, indicating poor stability of the electron-ion interface reaction. In Comparative Example 2, the pre-insertion of zinc ions effectively reduced the charge transfer resistance and increased the electron transfer rate, but the electrode reaction diffusion rate decreased significantly. Comparative Example 3 confirmed that the introduction of sodium anthraquinone-2-sulfonate indeed made the system's charge transfer resistance more stable. During 0-1000 charge-discharge cycles, the charge transfer resistance remained almost unchanged, and the zinc ion insertion-extraction electrode reaction process was stable. Finally, the Zn_AQ_VOH composite system exhibited a highly stable electrode-electrolyte interface and electron-ion diffusion barrier (Rct remained almost unchanged, only 4Ω), proving that modifying the cathode material with zinc ions and sodium anthraquinone-2-sulfonate can stabilize the crystal structure of the cathode material.

[0057] The cathode materials prepared in Example 3 and Comparative Examples 1-3 were subjected to constant current charge-discharge (GCD) tests using the Blue Electric CT3002A microcurrent testing system. The results are as follows: Figures 8-10 As shown;

[0058] Depend on Figure 8 As can be seen, under the conditions of 5 cycles of GCD testing at current densities of 0.5 A / g, 1 A / g, 2 A / g, 4 A / g and 5 A / g, the average discharge capacity of the cathode material prepared in Example 3 was 392.18 mAh / g, 338.2 mAh / g, 285.7 mAh / g, 216.3 mAh / g and 183.62 mAh / g, respectively. Moreover, after recovering to 0.5 A / g, the capacity immediately recovered to 373.54 mAh / g, which is much higher than the data of the cathode materials prepared in Comparative Examples 1 to 3. Therefore, the cathode material prepared in Example 3 showed higher specific capacity and better recovery performance, thus demonstrating better electrode structure stability.

[0059] Depend on Figure 9It can be seen that under the long-cycle test conditions of 1 A / g and 200 cycles, the highest discharge capacity of the cathode material prepared in Example 3 is 260.97 mAh / g, and the capacity retention rate after 200 cycles is 82.5%, which shows excellent cycle stability. However, the average capacity of Comparative Examples 1 to 3 after 200 cycles is lower than that of Example 3, especially the average capacity of Comparative Example 1, which is only 90.53 mAh / g.

[0060] Depend on Figure 10 As can be seen, under the long-cycle test conditions of 5A / g and 2000 cycles, the highest discharge capacity of the cathode material prepared in Example 3 is 219.4mAh / g, and the capacity retention rate after 2000 cycles is as high as 80.5%, which further demonstrates that the vanadium-based cathode material prepared by the present invention has excellent cycle stability.

[0061] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0062] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a high-stable crystal face structure vanadium-based positive electrode material, characterized in that, It comprises the following steps: Step S1, adding vanadium pentoxide powder into a beaker, then adding deionized water to stir and mix for 10-30 min, then adding zinc sulfate and sodium anthraquinone-2-sulfonate to stir and mix for 10-30 min, and finally adding hydrogen peroxide to stir and mix, to obtain a modification solution; Step S2, adding the modification solution into a reaction kettle, then adding the pretreated carbon cloth to immerse in the modification solution to perform hydrothermal reaction, reducing pressure, cooling to room temperature, washing with water for multiple times, and drying to obtain a high-stability crystal face structure vanadium-based positive electrode material.

2. The method for preparing a high-stability crystal face structure vanadium-based positive electrode material according to claim 1, characterized in that, The use amount ratio of the pretreated carbon cloth, vanadium pentoxide powder, deionized water, zinc sulfate, sodium anthraquinone-2-sulfonate and hydrogen peroxide is 10g:4.5-5g:562.5-625mL:0.35-0.5g:0.3-0.5g:4.5-5g.

3. The method for preparing a highly stable vanadium-based cathode material with a crystal plane structure according to claim 1, characterized in that, The pretreated carbon cloth is prepared by the following method: The carbon cloth is sequentially cleaned with hydrochloric acid, acetone, ethanol and deionized water, and then dried to obtain the pretreated carbon cloth.

4. The method of claim 2, wherein the vanadium-based positive electrode material having a high-stable crystal plane structure is prepared by the following steps of: The purity of the vanadium pentoxide powder is 90-98%. ​ 5. The method for preparing a highly stable vanadium-based cathode material with a crystal plane structure according to claim 1, characterized in that, The temperature of the hydrothermal reaction is 120-140℃, and the time of the hydrothermal reaction is 6-10h.

6. A high-stability crystal face structure vanadium-based positive electrode material, characterized in that, The preparation method is prepared according to any one of claims 1-5. The preparation method is prepared according to any one of claims 1-5.

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